1. Field
Example embodiments relate to a method of detecting a defect on an object. More particularly, example embodiments relate to a method of detecting a defect generated, or otherwise present, on a semiconductor substrate.
2. Description of the Related Art
Generally, semiconductor devices are manufactured by various processes including a deposition process, a patterning process, a chemical mechanical polishing (CMP) process, a cleaning process, and other processes. Each process can introduce various types of defects on the semiconductor substrate, which can adversely affect the resulting semiconductor device. Therefore, a detection process for detecting the defects is performed so that decisions can be made for rectifying the defects, thereby improving device yield and reliability.
According to a conventional method of defect detection, a semiconductor substrate can be divided into a plurality of inspection regions. An inspection image of an inspected region can be compared with a reference image of a nearby inspection region to identify defects in the inspected region. In other words, the presence of defects in the inspected region is determined using only a single reference image.
In contemporary memory devices it is common for both a cell region and a peripheral region to be present in each of the dies on the semiconductor substrate. The cell region and the peripheral region can quite commonly have different reflective properties and scattering coefficients with respect to the incident inspection light. Further, certain differences in properties such as layer thickness can exist between dies located at a central portion and an edge portion of the semiconductor substrate. That is, certain regions of the semiconductor substrate can have clearly discriminated brightness properties.
Thus, when defects present in inspection regions having different brightness properties are detected using only a single reference image, reliability of the defect detection process can be significantly low. That is, when the defect detection process is performed using the single reference image having a single brightness property despite the fact that the inspection regions can have different brightness properties, an inspection region without a defect can be determined to be abnormal or an inspection region with a defect may be determined to be normal. As a result, the conventional inspection method may vary in effectiveness with respect to position of the inspected region on the semiconductor substrate or with respect to the brightness of the inspected region.